时间：2011-03-11 23:11来源：蓝天飞行翻译 作者：admin 点击：次
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By the proper positioning of the three switches, any value of resistance between 0.1 ohm and 99.9 ohms may be selected. decalage. The difference in the angles of incidence between the two wings of a biplane. If the upper wing has a greater angle of incidence than the lower wing, the decalage is positive. If the lower wing has the greater angle of incidence, the decalage is negative. decarbonizer. A solvent used to soften carbon deposits that have formed on metal surfaces. Carbon formed on engine parts because of the coking action of oil is hard and is baked onto the surface of the metal. It must be softened with a decarbonizer before it can be removed. Some decarbonizers are used cold, and others are heated to make them act faster. decay (condition of vibrations). To gradually decrease the amplitude of vibrations. A damped oscillation is one in which the amplitude of the oscillations decay, or become less with time. See damped oscillation. decay (wood defect). The breakdown, or decomposition, of the structure of wood fibers. Wood that shows any indication of decay must be rejected for aircraft structure. Decca navigation system. A long-range, hyperbolic navigation system that allows a navigator to establish a line of position by measuring the phase difference between a master signal and three slave signals. These medium-frequency continuous-wave signals are transmitted simultaneously from a land-based master station and three slave stations. decelerate. To decrease the speed of a moving object; to slow it down. deceleration. The amount the velocity of an object, measured in feet per second, is decreased by a force during each second it is acted upon by that force. Deceleration is normally expressed in terms of feet per second, per second (fps2). deci. The metric prefix that means one tenth. For example, a deciliter is one tenth of a liter. decibel (acoustic measurement). The basic unit of sound intensity equal to one tenth of a bel. For practical purposes, one decibel (abbreviated dB) is the lowest amount of sound pressure that can be heard by a normal human ear. Sounds above about 130 decibels normally cause pain. decibel (electrical measurement). A measurement of the ratio of two electrical powers. One decibel is equal to ten times the logarithm of the ratio of the two powers. See bel. deciduous. A type of tree that sheds its foliage at the end of the growing season. Hardwoods come from deciduous trees. decimal digit. Any of the Arabic numerals 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. decimal fraction. A proper fraction whose denominator is a number which is a power of ten. The value of the denominator is not written, but it is indicated by the position of the decimal point. One digit to the right of the decimal point means that the denominator is 10 (0.1 = 1/10); two digits to the right of the decimal shows the denominator is 100 (0.01 = 1/100), and three digits indicates 1,000 (0.001 = 1/1,000). |
